The present invention relates to an ink jet printer head. In particular, the present invention relates to an improvement of a nozzle surface of the ink jet printer head which selectively attaches ink drops to a recording medium.
High speed printing, low noise and high print quality are being demanded of ink jet printers. Also high performance capability is demanded of an ink jet printer head. In order to satisfy these demands, conditions of the nozzle surface of the ink jet printer head plays an important role.
Often, ink, paper dust and the like attaches on the nozzle surface. When such attachments are present on the nozzle surface, the ink drops which are being ejected out of the nozzle are attracted to these attachments and the ink drops are ejected in a direction that is different from the original ejection direction. If the amount of such attachments is large, the proper ink drops are not formed. In order to resolve these problems, it has been considered important to provide ink repellant properties (e.g., water repellant property) to the nozzle surface. By providing ink repellant properties to the nozzle surface, attachment of ink and paper dust may be reduced. Methods in which silicon type compounds or fluoride type compounds are formed on the nozzle surface have been suggested as a technique to provide such ink repellant properties.
However, the nozzle surface on which silicon compounds and the like are formed has presented a problem in that the nozzle surface has poor resistance against various inks. The silicon type compound has a siloxane bond (Si--O) as part of its basic structure. The siloxane bond is easily cleaved by a base. Hence, the resistance of the nozzle surface has been weak against the inks containing alkaline components. In other words, the ink used for an ink jet printer contains water in which many components such as dye, solvent and surfactant are added. A dye is a salt made of acid and alkaline. The salt is ionized in the water and forms a base (ammonium ion, sodium ion, calcium ion and the like). Moreover, in order to improve penetration of the solvent into the paper, a solvent with high level of chemical activity such as one that melts the paper fiber is used. Such solvents naturally also have the function of decomposing the silicon compounds.
Moreover, the adhesive power of fluorine compounds with the nozzle surface is small. Hence, this created a problem such that compounds are easily peeled off from the nozzle surface by the cleaning operation (hereafter wiping) of the print head to wipe off the ink, paper dust and the like that are attached on the nozzle surface. There has been no simple method to reprocess the nozzle surface once the ink repellant film is removed from the nozzle surface. Hence, even if other parts of the ink jet printer head is operating normally, the entire ink jet printer head has to be replaced.
A first object of the present invention is to provide an ink jet printer head with water repellant property without substantial deterioration of its ink drop ejection capability, and to provide a method of making such an ink jet printer head.
A second object of the present invention is to provide an ink jet printer head which substantially maintains its water repellant property caused by wear of the nozzle surface, and to provide an ink for use therein.